The present invention relates to radiation sources adapted for Mossbauer investigations of chemical compounds employed for investigating structures of chemical compounds, studying chemical transformations of organic and inorganic chemical compounds as well as for analytical applications and in industry.
More specifically, the present invention relates to a radiation source for Mossbauer investigations of tellurium compounds.
Known in the art are radiation sources for Mossbauer investigations of tellurium compounds such as the binary tellurium compounds Zn.sup.67 Te.sup.125m and PbTe.sup.125m and such sources as Sb.sup.125 in Cu, l.sup.125 and .beta. --Te.sup.125m O.sub.3.
There are various methods of preparing such radiation sources. In the preparation of sources such as ZnTe and PbTe after the production of a chemical matrix from inactive compounds such as Zn.sup.67 Te.sup.124 and PbTe.sup.124, the matrix is exposed to irradiation in a reactor by means of thermal neutrons, whereafter, to eliminate radiation defects, the matrix is annealed at a temperature within the range of from 400.degree. to 500.degree. C for a period of from 1 to 3 hours.
Sources made of Sb.sup.125, l.sup.125 and .beta.--Te.sup.125m O.sub.3 require pre-irradiation of an isotopic raw material in a reactor, followed by special radio-chemical synthesis to obtain a required chemical form of the source.
The prior art sources and the methods of preparing the sources feature some disadvantages, among which the most essential are the following:
1. Sources such as ZnTe and PbTe, Sb.sup.125 in Cu have but a small probability of Mossbauer effect which, even at the temperature of liquid nitrogen, does not exceed 0.2 and at room temperature is at most 0.05. Furthermore, these sources have, as a rule a widened emission line as compared to the natural one (2.GAMMA..sub.n = 5.3 mm/sec) which is due to difficulties of obtaining a strict stoichiometric composition of these compounds used as a chemical form of the sources.
Sources using l.sup.125 also have a small probability of Mossbauer effect and may be used only in emission spectroscopy.
2. The source .beta.--TeO.sub. 3, though having good Mossbauer parameters, is difficult to prepare. To produce it, one should perform a complex radio-chemical synthesis of an unstable compound, viz. .beta.--TeO.sub. 3 which already at a temperature of about 100.degree. C is transformed into other modifications, whereby the effect becomes less pronounced and the emission line is widened. Moreover, to prepare this compound, conditions of a specialized radio-chemical laboratory are necessary.